The present invention relates to a combinatorial measuring method and apparatus for combining weighing data from a plurality of weighing machines, finding combined weights which are equal to a preset value or closest to such a preset value within an allowable preset range, and discharging articles from those weighing machines which have given such combined weights thus determined.
In conventional weighing methods of the type described, batches of articles are generally supplied only to those weighing machines which have discharged batches of articles, except when the weighing system starts operating. When no batch of articles is supplied to a certain weighing machine due to an uneven supply of articles to the weighing machines or for some other reason, that empty weighing machine is far less likely to be supplied with a batch of articles than the other weighing machines which are properly supplied with batches of articles. Therefore, once a weighing machine is accidentally left empty, it tends to remain empty for a long period of time. This causes a substantial reduction of the number of weighing machines taking part in the combinatorial weighing operations, so that the accuracy of the combinatorial weighing operation will be lowered.
Various attempts have been made to improve combinatorial weighing methods. The applicants of the subject application have filed Japanese Patent Application No. 55-162983 (corresponding to U.S. Pat. No. 4,396,078) which discloses a novel method of speeding up weighing operations while maintaining a given degree of accuracy of combinatorial weighing.
The natures of some articles is conducive to an uneven supply of articles to weighing machines. When this happens, a combination of weighing machines giving combined weights within an allowable preset weight range may not be available even after all predetermined weight combinations have been executed. To cope with this difficulty, there is known a method of additionally supplying a batch of articles to a weighing machine, and then combining article weights measured by the same group of weighing machines. This method requires a weighing machine supplied with additional articles to participate in a next combinatorial weighing operation. Therefore, the method cannot be incorporated in the foregoing method disclosed in Japanese Patent Application No. 55-162983 since with the disclosed method, weighing machines supplied with batches of articles are allowed to take part in combinatorial weighing only in a next combinatorial weighing cycle but one.
There has been a need for a method of finding a weight combination falling within an allowable preset range without impairing the high-speed weighing operation performed by the above disclosed method in the event of a failure of determining a combination of weighing machines which provide a weight combination within the allowable preset range.